The present invention generally relates to apparatus and methods for capturing lubrication fluid in a turbine engine and, more specifically, to apparatus and methods of capturing fluid from a fluid nozzle with a scoop rotating about a central axis.
Turbine engines and other machinery having components that rotate at several thousand revolutions per minute have bearing assemblies that support rotating shafts. Higher cycle temperatures and air temperatures within these engines may result in temperature increases in the rotor and bearings. As such equipment grows in size, larger bearings may be included within such equipment to provide increased support and performance for turbine engines and other such equipment.
To minimize the effects of increased temperatures, friction, and the like, which may occur in a turbine engine, bearing assemblies include lubrication systems that provide lubricant to the bearing assemblies supporting rotor shafts, which may in turn reduce wear to the bearing assemblies and which may provide cooling to the bearing assemblies. A typical bearing assembly may include a split inner ring mounted to a rotor shaft, an outer ring, and a rolling element supported therebetween. The lubrication system may include an oil jet to supply oil to a shaft having a plurality of axial grooves in the shaft for supplying oil to the bearing assembly.
In such lubrication systems, the oil is transferred from a stationary location to a rotating shaft. One method to do this is to use a radially rotating scoop in combination with a jet that sprays the oil at a rotating scoop. The scoop may have a plurality of blades that captures at least a portion of the oil being sprayed from the jet. The captured oil may then be directed to a plurality of axial slots disposed in the rotating shaft, which eventually terminate in a location to provide the captured fluid to the bearing.
For example, U.S. Pat. No. 6,409,464 (“Fisher 464”) is directed to a method of supplying oil to bearings which includes supplying oil through a plurality of scoops to a rotor shaft groove through at least one opening that extends between the rotor shaft inner and outer surfaces of the scoops. The rotor shaft includes a plurality of scoops extending between the rotor shaft inner and outer surfaces. However, the scoops disclosed are conventional flat blade scoops that merely extend between rotor shaft outer and inner surfaces. This reference does not recite particular scoop geometries which maximizes the capture and distribution of oil.
U.S. Pat. No. 6,682,222 (“Fisher 222”) is directed to a bi-directional oil scoop for bearing lubrication. Fisher 222 discloses a scoop having a constriction over which the oil sprayed from a jet into the scoop must pass. The constriction acts as a potential barrier for the oil. The portion of the scoop radially past the constriction is arranged to be downstream of the constriction in a centrifugal sense. This constriction thus prevents oil from flowing back towards the jet once it has passed this constriction. However, similar to “Fisher 464” above, this reference discloses conventional flat blade oil scoops which protrude tangentially from the shaft inner surface to the shaft outer surface. This reference does not recite a particular scoop geometry that maximizes the capture and distribution of oil.
Radial oil scoops known in the art are not 100% efficient, and the efficiency can depend on shaft speeds. Low efficiency oil scoops may thus result in extra oil inside bearing sumps of the engine, which may decrease engine efficiency by wasting power due to oil churning. To produce the extra flow of fluid from the jet to compensate for the inefficiency of oil scoops, the oil system components size and weight may be increased relative to the size required for the captured amount of fluid. This may also negatively impact power to weight ratio of the engine. As can be seen, there is a need for an improved apparatus and method to capture fluid using a high efficiency scoop rotating about a central axis, preferably a scoop which at a given shaft speed and fluid jet location and velocity has an increased efficiency relative to known flat blade scoops present in the art.